This invention relates to a method of treating metal melts by the addition thereto of chemically active substances or alloying elements wherein the metal melts are set in motion in a suitable, substantially cylindrical vessel by means of electromagnetic force. This invention further relates to an apparatus for carrying out this method.
Metal melts, in particular iron and steel melts, are conventionally treated by intimate mixing with chemically active media, which are added to the melt in a solid, liquid or gaseous state. For example, pig iron melts are desulphurized or dephosphorized by being mixed with suitable media, e.g. soda or basic oxidizing slags. Steel melts are similarly treated (e.g. for deoxidation or sulphurization), by being mixed with pulverulent substances or slags. Such mixing is usually accomplished in ladles. Alloying elements are also introduced into metals by being intimately mixed therewith. Similarly, chemical reactions can be achieved by intimate mixing of solid substances with metal melts. Thus, for example, coal can be gasified by being introduced into pig iron melts, which are simultaneously or subsequently oxidized. Also, as previously proposed in Luxembourg Pat. No. 81,330, dusts containing zinc or zinc and lead (blast furnace dust) are treated by being blown into a pig iron bath (with or without added carbon). This process both permits separation of lead and zinc, and enables the iron to be recovered in reduced form.
A conventional method of introducing pulverulent or granular substances into metal baths comprises suspending the substances to be introduced in a stream of gas and introducing them onto or into the bath by means of lances. However, it has been found that during this process of blowing, substantial quantities of the substances to be treated are also carried out by the gas stream and are thus lost to the reactions.
It is likewise known to carry out metallurgical reactions such as desiliconization, dephosphorization or desulphurization of pig iron in the tapping spouts of the blast furnaces by blowing in or top-blowing oxidizing or reducing substances.
It is furthermore known that counter-current operations can be carried out with conventional electromagnetic spouts. It has however been found that, in most cases, only an inadequate mixing effect can be achieved with this procedure.